Loading of conductors



June '10, 1930. J. J. GILBERT 1,763,043

LOADING 0F CONDUCTORS Filed. Nov. 6. 1928 2 :1 I I "III" )llllll llllllNVEN TOR J. J, GILBERT ATTORNEY marine cables, This applicationfis'a'contherethrough.

Patented June 10, 1930 I warren-stares JOHN GILBERT, on noneLAsron;nEw..YoRK,-Assrenon r0 :eELLrn nPHonE-LAB ORATORIES, rncoaronaran, orNEW YORK, N. Y.,-A CORPORATION or NEW'YORKT' v LoAnrneor connnc'ronsApplication filed November 6, 1928; sralmysn oi.

This invention relates to longgloa ded subtinuation in. part ofapplication, Ser.v No. 696,981, filed March 5,19245 a An object oftheinvention is to reduce impedance irregularities in a'loaded cable. 1

Another object of the invention is to re duce signal distortion whichresults from variations in the impedance of a'signaling conductor withvarlationsin'the current flowing In long submarine rents must be appliedat one ,end'in order that signals of suitable strength may be re-,

ceived at'the distant end; If the conductor is loaded'with magneticmaterial the permea bility and hysteresis losses of which'vary withthe-magnetizing forceflarge variations in the Y current and hence in themagnetizing*fforce in the terminal sectionslmay cause the induc= tanceand resistance due to the loading" material to vary between wide limits.As. a

result of these variations in the inductance and resistance *of theconductor,- theatt'ensending current'pr'oduces a negligible increase incurrent receivedat the distant end of the cable. Also it is :dificult toconstruct an artificial line that Will simulate such a cable withsufiicient exactness for duplex telegraph operation. If the cable'isdesigned for telephone or carrier frequency operation there is theadditional objection that thevarying impedance producesintermodulationbetween difierenttelephone and carrier frequencies with resultantdistortion.

In accordance with this invention the same magnetic composition, withinthe limits of manufacturing variations, may be employed as loadingmaterial upon the entire conduce tor or upon two or more sections havingdifferent degrees of variability of inductance with current. Theadvantages of having ma terial of more uniform inductance on certaincable sections is therefore attained Without the necessity of selectingdifierent material to secure the desired result. This is accomcablestheoverall atten nation is so great that relatively large curveloped in theloading material 'a lower plished by' heat treating certain sections in.Sucha manner as to cause'the loadingma terial thereon to have moreconstant permeability and lower hysteresis losses,'over a wide range ofm'agnetiz'ingforces, thanthat on thecent'ral sections." Whenfheattreated to have more constant permeabilitythe'loading material mayhavelower initial permeability, r

which would reducethe effective inductance of the conductor; thishowever, maybe comf' pensated by increasingthe thickness of loading onthe terminal sections.

' .A' cable conductor in accordanc By 'wayof describing concreteexampleslof practicing the present inventionwe 'shall first" considerits applicationto a"continu0' uslyj loaded telegraph cable. Inaccordance with the invention the central portions of said 7 cable- 'maybejloaded 'with a magnetic mate-- rial containing about .7 8% nickel andthe balance'chiefly-iron, with or withoutfa ma-j terial for increasingthe resistivity-of the" 1 loading material; in'whi'ch a permeability ofthe order of 4,000 for magnetizing forces of about 0;001 gausshas beendeveloped by suit ableheat treatments such as are describedin EU. Z S.Patents 1,586,883 and 1586384, "both granted June 1, 1926 to G.VViElmeI-IT The terminal sections "extending; over a length of aboutmiles from'both'eable ends, -inaccordance with the. invention,-areloaded with the same magnetic material in which however, apermeability of about 2,000 to 4:,000 has been developed by giving itaiheat treatment atalower temperature. 5

' For example the conductor with theloada ing' tapes'wrap'p'edthereabout may bedrawn.

in the direction oi": its longitudinal axis through an annealing furnaceSUChI 'aS'fde scribed in the patents referred .to-a'aboveior;

such as described in-U. SfPatent'1,586,887,"

600 C. In this manner-there will be de more constant; permeability.

ent invention to a continuously loaded tele Consider now theapplicationot thelpr'esgranted June '1, 1926; to G. W. Elmen;-'t-theannealing temperaturev being. only about phone cable. In accordance withone embodiment of this invention the central sections of the cable maybe loaded with a magnetic material comprising about 45% nickel, 30% ironand cobalt, with or without a fourth substance such as 1 to 10% ofmolybdenum'or chromium, replacing equal amounts of iron, for increasingthe resistivity. When this particular composition without the fourthelement is heat treated at about 1100 C. for one hour and cooled in sucha fashion that it.

' magnetic induction in passing from a very small value to 100 gauss was5% in the first case it was only 1% in the second case. Furthermore, thehysteresis loss of the sample thus treated was almost negligible for aflux density up to about 370 gauss. In accordance with the principles ofthe invention the constancy of permeability possessed by this material,together with its low hysteresis loss, reduce the variations ofinductance and effective impedance of the terminal sections of theloaded conductor.

In the accompanying drawings is illustrated a specific embodiment ofthis inven-.

tion in which all the sections of a continuously loaded submarinesignaling conductor 1 are loaded to have the same inductance. Forexample, the central'sections may be loaded with one layer 2 of theabove-mentioned composition (45% nickel, 30% iron, 25% cobalt), heattreated to have an initial permeability of 800; this permeability can bedeveloped by using a cooling rate a little faster than the first oneabove specified. The terminal sections, however, are loaded with twoequally thick layers 3 of the same composition, but heat treated, asspecified above, to have an initial permeability of 400.

However,it is not essential that the sections have the same inductancebut the heat treatment may be varied so as to obtain differentconstancies of permeability on different sections while the thickness ofthe loading may not be correlated to give the same inductance on all thesections.

' The constancy of permeability may be varied in more than two stepsalong the loaded conductor, and the thickness of loading and thepermeability do not have to have inverse integral ratios. Any desiredpermeability and any desired total thickness of loading divided into anydesired number of equal or unequal layers may be employed.

The invention is not limited to the particular combinations of magneticproperties and heat treatments or embodiments disclosed herein; it isunderstood that various other combinations may be employed by thoseskilled in the art without departing from the spirit and scope of theinvention.

What is claimed is:

1. The method of improving the transmission characteristicsof along'signaling conductor loaded with a material of substantiallyidentical which method comprises heat treating the terminal sections ofsaid conductor to have greater constancy of permeability than the centersections.

2. Method in accordance with claim 1, characterized in this that inloading the terminal sections a greater thickness of loading material isapplied than in loading the center sections.

3. A long submarine signaling conductor loaded with magnetic material ofsubstantiallyv identical composition throughout its length, in which theloading material on a e terminal section has a materially greaterconstancy of permeability than the loading on a center section for agiven induction.

4.. Conductor as defined in claim 3, characterized in this that theloading material on a terminal section has a greater thickness than theloading on a center section. I 5. A long signaling conductor havingsections loaded with magnetic material of substantially uniformcomposition, said sections having substantially equal effectiveinductance for small signaling currents but having a materiallydiiferentrate of variation of inductance with variation of current overthe range of current values traversing the sending terminal of saidconductor.

In witness whereof, I hereunto subscribe my name this 3rd day ofNovember, 1928. JOHN J. GILBERT.

composition throughout,

